The obscure effect can be applied to only a rectangular area of the clip. Is it possible to simply copy that mechanism to other effects or is my assumption way too simple?* Is it possible to apply a video effect only to a (spatial) part of a clip ? The area can be restricted to a rectangle. Is it what the "region" transition of mlt is for?Yes, that is probably a much wanted feature, but it has not been implemented in Kdenlive yet.